This application relates to an air induction system for an engine having an expansion reservoir to cancel noise wherein the volume of the reservoir may be varied to accommodate different engine conditions.
Modern engines for vehicles are the subject of a good deal of engineering. One feature that modem engineers attempt to address is the reduction of induction noise by providing a resonant chamber adjacent an air intake system leading to the engine. As is known, as air is induced into the engine, noise comes from the engine outwardly through the air inlet lines. Known resonators are finely tuned to cancel this noise. However, the noise varies between high and low engine speeds. Typically, the design of these resonators has been a compromise to achieve a single volume which addresses neither the highest or lowest speeds as optimally as would be desired.
Typically, the resonators include an air reservoir of a fixed volume connected through a neck to an air flow line leading to an engine. The fixed volume is finally designed to address a certain type of engine noise. However, the engine noise will vary between high and low speeds, and thus this volume is typically not optimally designed for either speed.
In the disclosed embodiment of this invention, a resonator chamber system provides variable volumes, and may be switched between at least two modes at high and low engine speeds to provide an optimized noise reduction for each speed. In this regard, the chamber volumes can be designed to provide Helmholtz resonators with a desired volume for each of high and low engine speeds.
In one embodiment, a pair of necks connect to a volume of a resonator body. The preferred embodiment of this invention has a moving flap that can selectively communicate or separate two volumes to provide finely tuned chamber volumes. Seal surfaces are provided on opposed faces of the flap valve. A stop surface is formed within an inner body of the resonator chamber housing.
A pivot point is preferably positioned adjacent an upper wall of the body. Linkages pivotally attach to the pivot linkage, outwardly of the body. The linkage is connected to an actuator which is connected to an engine control. The engine control actuates the in response to variations in engine speed.
The flap valve is movable between a first position at which it closes the second neck, and thus communicates the two chambers together to provide a large volume chamber. This is particularly valuable at low speeds wherein there is a lower frequency which is to be reduced. The engine control will move the actuator, and thus the flap valves to communicate the chambers at lower speeds. However, as the engine is moved to higher speeds, the flap valve is moved to a position at which is isolates the two chambers. Thus, the two necks communicate with separate chambers. This configuration is better suited to eliminate and reduce noise associated with higher frequency and engine speeds. Again, the engine control is operable to move the flap valve as necessary.
In other embodiments, the flap valve moves to direct the flow of air to the engine through one of two passages. The other passage then becomes the resonant chamber. The two passages have different volumes and shapes, and thus the two different passages can be designed to create the tuned configuration most optimum for the two engine conditions.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.